Cited as a reference
Replacing My Car Battery with Capacitors! 12V BoostPack Update
Why people recommend it
A hobbyist replaces a car battery with a supercapacitor pack; cited as proof it can start a car, with answerers noting it drains quickly with the engine off.
Watch for: the lithium hybrid version was damaged jump-starting a mower
In their words
Using supercapacitor as starter battery is fully feasible and was tried by enthusiasts in practice, see example.
Juraj on electronics.stackexchange.com, Nov 2016. CC BY-SA.
I'm interested building my own battery pack using a series of super capacitor, something like this:
Pennf0lio on electronics.stackexchange.com, Aug 2013. CC BY-SA.
There's examples on youtube such as this video which prove it works on cars.
alphasierra on electronics.stackexchange.com, May 2017. CC BY-SA.